Retention of moisture

Ground covers in banana plantations are favorable for retention of moisture. A desirable ground cover consists of broad-leafed plants, but grasses predominate in many areas. Chemical control of grasses is not favored because banana plants are sensitive to chemicals, so the areas are hand chopped at frequent intervals. The banana plant is a rapid growing, highly succulent, perennial herb that is easily damaged with as little as 7.5 pounds of CMU [3-(p-chlorophenyl)-l,l-dimethylurea] per acre applied in a semicircular strip within 2 feet of the plant. This plant is sensitive to 2,4-D and can be injured by low concentrations. 

This list includes several aliphatic and aromatic amines that are soluble in water and therefore are not significantly affected by retention of moisture on the silica gel sorbent tube. In some cases, such as with chloroacetaldehyde, collection of moisture may even improve the collector. Chloroacetaldehyde forms a very stable hydrate when collected from humid atmospheres with silica gel, besides being efficiently collected from a dry environment. 

Humectants hygroscopic substances incorporated in a product to promote retention of moisture, including moisture retention agents and antidusting agents. 

All equipment should be designed and constructed in a manner that prevents the retention of moisture (unless it is designed to deliberately stay full of sterile water), ingress and harbourage of vermin and soil and to facilitate inspection, servicing, maintenance and cleaning. 

Fireproofing or insulation. Such barriers must be weather-sealed and intact to prevent collection and retention of moisture against metal surfaces that could corrode. 

The addition of phosphate — pyro-, tripoly-, and hexametaphosphate — also protects cooked meat from auto-oxidation. Ortophosphate gives no protection. The mechanism by which phosphates prevent autooxidation appears to be related to their ability to sequester metal ions, particularly ferrous iron, which is the major prooxidant (Pearson et al., 1977). The addition of NaCl increases retention of moisture in meat and meat products. 

Humectant A chemical compound or substance that promotes the retention of moisture. 

Retention of moisture in polymer substrates or adhesives, especially in the presence of chloride or other ions, corrodes thin-film metallization such as nichrome resistors or aluminum conductors (further discussed in Chapter 6). Other limitations in using aqueous or semi-aqueous solvents include ... 

Bimetallic corrosion is more severe under immersed conditions than in the atmosphere. In the latter, attack occurs only when the bimetallic contact is wet this depends on many factors, such as the presence or retention of moisture in crevices, the effectiveness of drainage, and the speed of evaporation. The relative size of the areas of the metals that remain wet in the vicinity... 

Under-deposit attack or poultice corrosion may occur when a metal is locally covered by foreign, absorbent (organic or inorganic) materials [40,45]. In this case, attack can proceed even when the bulk of the system is dry due to retention of moisture in the poultice. The corrosion mechanism is similar to crevice corrosion in that the deposits act to limit the migration of oxygen to the covered area. This leads to acidic shifts in pH, concentration of Cl ions in the shielded area, and a shift to a more active corrosion potential under the deposit. Local corrosion rates can be very high due to the large cathode-to-anode area ratio. 

Several other mechanisms have been suggested by Stock and Holloway [125] for uptake activation (1) Prevention of crystal formation in deposits. It is often assumed that the foliar uptake of an agrochemical from a crystalline deposit will be less than that from an amorphous one. (2) Retention of moisture in deposits by humectant action. The humectant theory has arisen mainly from the observation... 

Shapes that, contrary to their function, retain corrosive combinations of air and electrolyte should be avoided. The designed product should neither collect nor retain unwelcome compound corrosive media within their form and frame. Access and retention of unwelcome solid contaminants or waste, which may act within the designed form by absorbence and retention of moisture or by abrasive action, should be avoided by the correct selection of form and arrangement. 

An absorbent material is akin to a sponge in that it can draw fluid into itself and retain this fluid within its structure, and the fluid can only then desorb by a change in phase (such as evaporation or drying). In this sense, it can act as a Alter by removing liquid droplets, for example, provided that they wet the absorbent. Thus, an untreated paper, being an absorbent material, could filter out water droplets from an air stream. However, its usefulness as a practical filter in such a case would be very limited, both as regards to retention of moisture, as it would soon achieve the maximum possible absorption capacity, and to mechanical strength, as it will be weakened by the moisture content (which may also act as a solvent for any binder in the paper). 

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